Continuous process for the production of alfin polymers by polymerization of alfin monomers in an organic solvent and for recovering and recycling solvent

ABSTRACT

A CONTINUOUS PROCESS FOR THE PREPARATION OF ALFIN POLYMERS IS PROVIDED, EFFECTING POLYMERIZATION OF THE MONOMER BY AN ALFIN CATALYST IN THE PRESENCE OF A MOLECULAR WEIGHT MODERATOR, TREATING THE ALFIN POLYMER REACTION MIXTURE WITH AN ORGANIC ESTER TO CONVERT SODIUM ACETYLIDES AND SODIUM CYCLOPENTADIENES TO ACETYLENIC CYCLOPENTADIENIC ALCOHOLS SEPARATING UNREACTED MONOMER, VOLATILE LOW POLYMER, ALCOHOLS AND SOLVENT, THEREAFTER PURIFYING SOLVENT AND RECYCLING IT AND OPTIONALLY THE MONOMER FOR REUSE, AND WASHING AND DRYING THE ALFIN POLYMER. IN THE PROCESS OF THE INVENTION, MOLECULAR WEIGHT OF THE POLYMER IS CONTROLLED BY ADJUSTMENT OF THE PROPORTION OF MOLECULAR WEIGHT MODERATOR. NO OTHER MODIFICATION OF REACTION CONDITIONS, PROPORTIONS OF CATALYST, AND OTHER PROCESS VARIABLES IS NECESSARY.

Feb. 8, 1572 T. B. BABA CONTINUOUS PROCESS FOR THE PRODUCTION OF ALFINPOLYMERS BY POLYMERIZATION OF ALFIN MONOMERS IN AN ORGANIC SOLVENT ANDFOR RECOVERING AND RECYCLING SOLVENT 3 Sheets-Sheet 1 Filed March 6,1970 whJ m 0.04 0 mh zm 0-04 m 55w a So Emu? N m wzmafizwmods owgthwmam2:34 3 2m no $5: 0 1 31E 0 I m wwzmipw outfifiwmnm No mo 5 x N 3183 vomw 3 0Q Qw aOn Ow Q of mm uzmiaomm 6132 43058.

z z. muzozoz muzozoz f um Feb. 8, 1972 T. B. BABA CONI'lNUOUS PROCESSFOR THE PRODUCTION OF ALFIN POLYMERS UY IOLYMEHIZATION OF ALFIN MONOMERSIN AN ORGANIC SOLVENT AND FOR RECOVERING AND RECYCLING SOLVENT FiledMarch (5, 1970 3 Sheets-Sheet 2 Z- 3 1?. x n n m8 5 E z. whim 92 m I n2635 428 2 u l- 9 25 904 a 35K o whu m 904 m So Emmi Q: 65; o

02 H wozu 35:

9 m Q Q:

m E m: o an? N2] q mzew Q MZON z. 4018 Feb. 8, 1972 T. B. BABA 3,540,979

CONTINUOUS PROCESS FOR THE PRODUCTION OF ALFIN POLYMERS BYPOLYMERIZATION OF ALFIN MONOMERS IN AN ORGANIC SOLVENT AND FORRECOVERING AND RECYCLING SOLVENT Filed March 6. 1970 I5 Sheets-Sheet 8ww zmkmxm Qwmm 552E mjomQo whim 9% o 2.5340 mmhSs Q3 wow 03 5 EN WN 9%wmuSE oh Em a .53 0 N A mmw L Q NW 5533 Nwm ww tohw kZM Om EN 923 SN 2.

20C. q ktmh mm United States Patent 3,640,979 CONTINUOUS PROCESS FOR THEPRODUCTION OF ALFIN POLYMERS BY POLYMERIZATION OF ALFIN-MONOMERS IN ANORGANIC SOLVENT AND FOR RECOVERIN G AND RECYCLING SOLVENT' Theodore B.Baba, 32 Standish Road,

Hillsdale, NJ. 07642 Continuation-impart of application Ser. No.740,158, June 26, 1968. This application Mar. 6, 1970, Ser.

Int. Cl. C08d 3/02 U.S. Cl. 260-821 26 Claims ABSTRACT OF THE DISCLOSUREA continuous process for the preparation of alfin polymers is provided,effecting the polymerization of the monomer by an alfin catalyst in thepresence of a molecular weight moderator, treating the alfin polymerreaction mixture with an organic ester to convert sodium acetylides andsodium cyclopentadienes "to acetylenic cyclopentadienic alcoholsseparating unreacted monomer, volatile low polymer, alcohols andsolvent, thereafter purifying solvent and recycling it and optionallythe monomer for reuse, and washing and drying the alfin polymer.

In the process of the invention, molecular weight of the polymer iscontrolled by adjustment of the proportion of molecular weightmoderator. No other modification of reaction conditions, proportions ofcatalyst, and other process variables is necessary.

This application is a continuation-in-part of application Ser. No.740,158, filed June 26, 1968 now abancloned.

This invention relates to a process for the continuous production ofalfin polymers, and more particularly to a continuous process for theproduction of alfin polymers from the monomer in the presence of asolvent, treating the alfin polymer reaction mixture with an organicester, and recovering and recycling solvent and, optionally, unreactedmonomer.

Morton and coworkers in a series of papers in the Journal of theAmerican Chemical Society, starting in 1947, describe an organoalkalimetal catalyst for the polymerization of olefins and particularly dieneswhich they term an alfin catalyst, Journal of the American ChemicalSociety 69, 161; 167; 950; 1675; 2224 (1947). The name alfin is takenfrom the use of an alcohol and an olefin in their preparation. Thealcohol, a methyl n-alkyl carbinol, usually isopropanol, in the form ofthe sodium salt, the olefin, also in the form of the sodium salt, and analkali metal halide, form a complex that constitutes the catalyst.

These catalysts are reported by Morton et al. to cause thepolymerization of butadiene, isoprene and other dienes, alone andtogether with other copolymerizable organic compounds, in most casesolefinic in nature. The catalyst was discovered in the course of a studyof the addition of organosodium compounds to dienes. Later on, Mortonsummarized the work done up until 1950 in Industrial and EngineeringChemistry, 42, 14881496 (1950).

Exemplary of early interest in the use of alfin catalysts is U.S. Pat.No. 2,592,301, patented Apr. 8, 1952 to Robert G. Linville. Using abatch technique, Linville formed polymers of 1,4-dicyano-2-butene bysubjecting the monomer to polymerization conditions in the presence ofan alfin catalyst. The polymers were said to be useful as intermediatesfor the synthesis of polyamides for shrinkproofing wool carboxylicacids, etc.

3,640,979 Patented Feb. 8, 1972 Ice U5. Pat. No. 2,606,179 to Boyd,patented Aug. 5, 1952, describes the polymerization of ethylene, usingan alfin catalyst in an aliphatic hydrocarbon solvent. The

polyethylene produced was said to be distinguished by its clarity,hardness and stability, and had a molecular weight in excess of 20,000.

Foster in U.S. Pat. No. 2,841,574, patented July 1,

1958 claimed that vastly improved results in alfin-type polymerizationscan be obtained by using as the solvent certain ethers, acetals, andamides. Foster suggested that the polymerization was effected by anentirely dilferent reaction mechanism than theretofore obtained withalfin catalysts. Foster polymerized propenyl benzene, obtaining apolymer having a molecular weight of about 4500. Polybutadiene was alsoobtained, but the molecular weight was not given.

The elastomeric polymers obtained from dienes, alone or copolymerizedwith olefins, using alfin catalysts are termed alfin polymers or alfinrubbers. Because of the speed and ease of the reaction, these attractedconsiderable interest in the 1940s and early 1950s. However, the veryspeed of the reaction led to problems. The alfin rubbers have thedisadvantage of having an extremely high molecular weight, generally inexcess of 3,000,000, and frequently in excess of 10,000,000. As aresult, although these polymers are generally gel-free and have hightensile strength, superior abrasion resistance, and tear strength, theyare also very tough, and exhibit little breakdown and consequently poorbanding on the mill. Therefore, they are difiicult if not impossible toprocess using conventional equipment. Consequently, interest andresearch in the alfin rubbers until recently was minimal, and in theiroriginal form the alfin rubbers have found very little commercialapplication.

Diem, Patent No. 2,856,391, patented Oct. 14, 1958, describes alfin typepolymerizations obtained using a lithium alkoxide and an alkenyl lithiumcompound. The polymers were soft, and easily formed into smooth sheetson a rubber mill, in contrast to alfin polymers which requiredconsiderable mill breakdown and/or the addition of oils to produce asmooth sheet on the mill, according to Diem.

In all of the above patents, batch techniques were employed to producethe polymers. Batch techniques are however ineflicient, and diflicult toadapt to a commercial process. Patent No. 2,606,179 suggests that thesystem employed could be easily adapted for continuous polymerization,because the polymer settles to the bottom of the reaction vessel and maybe drawn oif therefrom, but in fact no continuous system is described.

Patent No. 3,197,448, patented July 27, 1965 to Gavlin, Hedman, andHubbard, describes the production of elastomers by subjecting propyleneand butadiene mixtures to the action of an alfin catalyst. A batchtechnique is used. There is no reference to a continuous process.

The difiiculties in attempting to prepare alfin polymers by a continuousprocess are outlined in part by Kizer, Klopfer and Burke in U.S. PatentNo. 3,074,924, patented Jan. 22, 1963. Kizer et a1. explain that alkalimetal polymerizations of elastomers have generally been restricted tobatch-wise or semi-continuous alternate batchwise systems, because ofthe long periods required to initiate polymerization and carry it to thedesired conversion. Kizer et al. noted that it had been proposed tocarry out such polymerizations in continuous tubes, with the materialskept stirred up and advanced along the tubes by internal screw means,but such reactors have not been satisfactory, because of the tendency ofthe sticky polymer to build up on the walls of the reactor and on thescrew, producing variable hold-up and consequently non-uniformity of thepolymer, and ultimately complete clogging of the apparatus, requiringthat it be taken out of service for clean-out.

' 'Kiz'ei et 211: describe a system in which the nonaqu eous liquiddiluent for the reaction mixture is established in a longitudinallyflowing elongated cylindrical stream, into which is introduced apolymerization catalyst, and then the monomer, conducting thepolymerization in an extended region of the stream, which is maintainedfree of agitation and at substantially nonturbulent laminar flow,diverting the inner portions of the body of polymer progressivelyoutwardly towards the periphery of the stream as the body flowslongitudinally, and progressively discharging the longitudinally-movingthin annular body of polymer and diluent from the outer periphery of thecylindrical stream using a special valve. Thereafter, the solvent isremoved.

It is not necessary, of course, to carry out a continuous polymerizationusing a single path system, such as described by Kizer et al., althoughif it were not for the difiiculties of carrying out such a system usingalfin polymers, it would definitely be a preferred one. Kizer et al.however, barely touch on the problems involved in converting thepolymerization of alfin rubbers to a continuous operation. It isnecessary to control not only the flow of the polymer through thesystem, but also its molecular weight. For this purpose, Kizer et al.add a shortstopping agent to arrest the polymerization at the desiredstage. Greenberg adds a catalyst deactivator for the same purpose.However, this is a serious complication, since the solvent system mustbe freed from catalyst deactivator, or else it cannot be reused. Thepolymer that is recovered must be freed frOm monomer, low polymer suchas dimer, solvent, and also catalyst residues. The catalyst (which is asolid) must be kept in a uniform suspension in the reaction mixturethroughout the reaction, if polymerization is to be uniform andcontrollable. At the same time, yield must be optimized, and this is noteasy to do while optimizing the other variables, such as solventrecovery.

A further problem in solvent recovery are the unsaturated impuritiesthat are present in small amounts with many monomers, particularlysubstituted acetylenes and cyclopentadiene. These can poison an alfincatalyst, and tend to accumulate in the solvent unless removed. Becauseof the small amounts, however, removal by fractionation or liketechniques is very diflicult.

Accordingly, it is not surprising that when alfin rubbers of relativelylow and medium molecular weights, ranging from about 50,000 to about1,250,000, were provided by Greenberg et al. via U.S. Patents Nos.3,067,187 and 3,223,691, all of the preparatory procedures describedwere batch procedures. There is a reference in the patent to acontinuous process, and it is of course possible to visualize theprocess as a continuous operation but in fact no details are given inthese patents as to how a continuous process in which monomer andsolvent are recovered and recycled could be carried out in practice.

The restriction on molecular Weight made possible by incorporation of amolecular weight moderator, a dihydroaromatic compound, with the alfincatalyst during the polymerization, for the first time made possible theproduction of alfin rubbers that were capable of being processesedeasily, thus avoiding the alternative techniques previously suggested,such as that of Pfau et al. U.S. Patents Nos. 2,964,083, granted Dec.13, 1960, and 3,074,902, granted Jan. 22, 1963, who endeavored to reduceworking Viscosity of the alfin polymers by the incorporation of liquidplasticizers, particularly petroleum hydrocarbon oil. Accordingly, theGreenberg et al. patents have renewed commercial interest in the alfinrubbers, and a commercial development, of course, requires a processthat would make it possible to prepare such rubbers as a continuousoperation.

In accordance with the instant invention, a continuous process for thepreparation of alfin polymers is provided,

" effecting the polymerization of the monomer at a temperature at whichthe reaction proceeds by an alfin catalyst in the presence of themolecular weight moderator, treating the reaction mixture with anorganic ester (which can be aliphatic, aromatic or cycloaliphatic) toconvert organometallic compounds such as alkali metal acetylides andalkali metal cyclopentadiene compounds to the corresponding acetylenicand cyclopentadienic alcohols, continuously separating unreactedmonomer, volatile low polymer and solvent from the alfin polymerreaction mixture, dispersing the resulting alfin polymer reactionmixture in water, steam distilling volatile materials from the resultingdispersion, and thereafter recovering solvent and optionally the monomerand recycling them for reuse, and washing and drying the alfin polymer.

The reaction with organic ester by converting acetylides andcyclopentadiene metal compounds into the acetylenic and cyclopentadienicalcohols makes it possible to separate these from the solvent, andprevent the corresponding acetylenes and cyclopentadiene which otherwisewould be regenerated when their organometal derivatives are brought incontact with water, from being distilled off with the solvent. If thisoccurs, they would be recycled with the solvent, and can react with anddestroy alfin catalyst by being converted again into their alkali metalderivatives. Moreover, with each recycling and each fresh portion ofmonomer, the content thereof will be increased, until a substantial lossof catalyst can occur. This is prevented by the organic ester treatment.

The reactions concerned are as follows:

M RCOOR -c-0M ROM f If o-0M H O -c-oH MOII J 2 2 R and R are organicgroups having from one to about twenty carbon atoms, and M is an alkalimetal. R can be an aliphatic, aromatic, or cycloaliphatic group, or anycombination thereof, having from one to twenty carbon atoms. Thearomatic groups will of course have at least six carbon atoms, and thecycloaliphatic groups at least three carbon atoms. A portion of thecatalyst may also react with the organic ester, depending upon theorganic ester used. To facilitate separation of the acetylenic andcyclopentadienic alcohols from the polymer and solvent, they should bevolatile liquids having a higher boiling point than either. Exemplaryesters are octyl acetate, methyl acetate, butyl acetate, decyl formate,stearyl propionate, methyl stearate, hexyl laurate, ethyl myristate,palmityl acetate, amyl acetate, propyl formate, propyl palmitate,dodecyl butyrate, methyl benzoate, amyl benzoate, octyl cyclohexanoate,ethyl phthalate, phenyl acetate, benzyl acetate, cyclohexyl propionate,cyclopropyl acetate, cycloheptyl acetate, phenyl butyrate, andcyclohexyl acetate.

The solvent and low boiling volatiles such as monomer can be separatedby various techniques. Prior to contacting the reaction mixture withwater, the low volatiles can be flashed at a reduced pressure andelevated temperature, to remove from about 10 to about 99% of suchmaterials, depending on the solids content of the mixture. 'Res'idual'volatiles including low polymer can be recovered by steamdistillationafterquenching the reaction mixture in water. This techniquepermits recovery of nearly all of the monomer (in the case of lowboiling monomers such as butadiene and isoprene) with a portion of thesolvent during the flashing, and quenches the reaction mixture in water,and recovers substantially all of the volatiles from the resultingdisperion, in part by steam distillation, and in part by vaporizationdue to the heat of-thesteam. Any salts formed or present arediss'olvedin the aqueous stream and purged. I In the process of theinvention, the molecular weight of the polymer is controlled byadjustment of the prop'orftionof, molecular weight moderator. No othermodi- =ficationof reaction conditions, proportions of catalyst, andother process variables is required. A catalyst deactivator and theresultant system contamination is thus unnecessary, eliminating aserious obstacle heretofore to realization of a continuous process.

"A further feature of the continuous process of the invention is theattainment of any desired Mooney value in the alfin polymer within therange from about 30 to about 110 after the polymerization has achievedabout 70% of completion, after which Mooney value does notchangeappreciably even if the reaction conditions be altered. Thisenables good control of uniformity of the polymer, and is unlike a batchprocess. The reason for this is not known, but it permits processing ofthe alfin polymer without deactivation ofthe catalyst and without regardto possible alteration inthe Mooney value of the .polymer. This rendersthe process extremely attractive for commercial application.

The invention also provides for linking alfin catalyst preparation andthe preparation of the sodium dispersion .used in preparing the alfincatalyst with the continuous alfin polymer process system, preferablyusing a common solvent or diluent in all three unit operations, andrecycling solvent and unreacted starting materials. In this way, a fullyself-contained system is provided in which the principal raw materialsconsumed are monomer, molecular weight moderator, alkyl halide andsodium.

FIG. 1 represents a flow diagram showing the sequence of unit operationsinvolved in a typical apparatus for carrying out the process of theinvention, and employing a flash step to recover low volatiles.

FIG. 2 represents a flow diagram of another embodiine'ncin which thereaction mixture is quenched with water.

3 represents a flow diagram showing still another embodiment of theprocess, utilizing apparatus for carry- "in g out the washing of thereaction mixture at the conclu- '-s'ion'- of-the polymerization, priorto quenching and solvent recovery.

These unit operations will now be considered in further detail. I

ALFIN -GATALYST PREPARATION The linking .ofthe preparation of the sodiumslurry used for the alfin catalyst and of the alfin catalyst formationwith the alfin'polymerization reaction represents an important aspect ofthe continuous process of the invention, and provides attractive savingsin operation. If in addition the same inertdiluent or solvent isemployed in the three steps, recovery of the diluent or solvent andrecycling at the conclusion of the polymerization are possible without asolvent fractionation step. The recycle solvent after monomer removal,and removal of catalyst alcohol and olefin, and water, can simply berecycled to each of these operations from a common line.

A particularly effective alfin catalyst is obtained when the sodium isemployed as a finely-divided dispersion in the inert diluent, in whichthe maximum sodium particle size is about 1 to microns, such as may beprepared on 'a Gaulin mill. When such finely-divided sodium is used,ordinary stirring devices may be employed, instead of high speedcomminuting equipment, in the preparation of the alfin catalyst.Moreover, catalyst activity can be more readily reproduced.

The amount of sodium in the dispersion is not critical, and can beadjusted to suit any alfin catalyst preparatory procedure that isdesired. Usually, a sodium concentration within the range from about '2to about 50% is satisfactory.

The inert diluent that is employed for dispersion of the sodium can beany liquid aliphatic or cycloaliphatic saturated hydrocarbon. Thehydrocarbon should be a liquid under the conditions during which thesodium dispersion and the alfin catalyst are formed. This requires thatit remain liquid at temperatures as low as 20 C.

and below, and at temperatures as high as 25 to C., or higher, whateveris the maximum temperature reached during alfin catalyst formation.

The satisfactory aliphatic hydrocarbon solvents that are also useful inalfin catalyst preparation and in alfin polymer formation includepentane, hexane, heptane, octane, nonane and decane, 2-methylpropane,2-methylbutane, 2,3-dimethylbutane; Z-methylpentane; 3-methylpentane,2,2-dimethylpentane; 2,3-dimethylpentane; 2,4- dimethylpentane; 2,2,4trimethylpentane; 2 methylhexane; 3-methylhexane; 2,4-dimethylhexane;2,5-dimethylhexane; 2,'2,4-trimethylhexane; Z-methylheptane;3-methylheptane; 2,3 dimethyloctane; 2 methylundecane; 2-methyldodecane; 2,'2,4-trimethyldodecane, etc., and mixtures thereof.While the examples have been listed with respect to the mono-, di-, andtri-methyl substituted aliphatic hydrocarbons, it should be appreciatedthat other lower alkyl-substituted hydrocarbons are consideredapplicable. Other suitable alkyl radicals include ethyl, isopropyl,butyl, etc. Especially suitable, since they are readily obtainable, areodorless mineral spirits, boiling range 349-406 F., commercial mixturesof branched aliphatic hydrocarbons, such as Isopar E, a material devoidof normal hydrocarbons, which typically has the composition:

Component: Weight percent 2,2,4-trimethylpentane 2.2 2,5-dimethy-lhexane2,4-dimethylhex'ane 2,3,4-trimethylpentane l 1.5 2,3,3-trimethylpent-ane21.1 3-methylhept-ane 3 3 .0 2,2,4-trimethylhexane 6.23-methyl-4-ethylhexane 3,4-dimethylheptane 5 7 2,3-dimethylhe-ptane3,3,4-trimethylhexane 15 other iso-components 13.7 I C naphtha+C 1.8

the C hydrocarbon mixture having the following composition:

and light alkylates which are devoid of n-hydrocarbons, such asSinclairs Light Alkylate, which has the following composition:

Component; Weight percent Z-methylbutane 10.0 2,3-dimethylbutane 8.22,4-dimethylpentane 5.8 2,3-dimethylpentane 7.9 2,2,4-trimethylpentane21.5

, 18 other C and C branched aliphatic hydrocarbons 46 6 Also useful arecycloaliphatic hydrocarbons, such as cyclohexane, cyclopentane, methylcyclohexane, and cycloheptane.

The sodium dispersion in an inert diluent can be employed in the usualway in any desired preparation of alfin catalyst. Typical preparationsof an alfin catalyst have been described in sufiicient detail in theGreenberg et al. Patents Nos. 3,067,187 and 3,223,691 and in Hoffman etal. No. 3,317,437, and in the Morton articles supra, so that fulldetails are not required here, and those skilled in the art Will knowfrom the following description how to utilize sodium dispersions inaccordance with the invention in such preparations.

As the secondary alcohol component, to form the sodium alkoxide, anymethyl n-alkyl carbinol having from one to about ten carbon atoms can beused, such as isopropanol, methyl-n-propyl carbinol, and methyl-n-butylcarbinol. Isopropanol is preferred.

The alkoxide will form at rather low temperatures, as low as --20 C.being satisfactory. There is no upper limit on reaction temperature.Consequently, the reaction temperature used is that suitable formetallation of the olefin.

The olefin has from about three to about ten carbon atoms, and shouldcontain the group -CH=CHCH Propylene is preferred, giving allyl sodium,but butene-l, butene-Z, pentene-l and hexene-l can also be used.Terminal olefins CH =CHCH are preferred. Activity may decrease as theolefin molecular weight increases.

The alkenyl sodium, sodium halide, and sodium alkoxide composing thealfin catalyst are prepared by reaction of the sodium slurry with thealcohol and the olefin in the presence of the dispersing liquid used forthe catalyst. This can be and preferably is the same as the inertdiluent used for the sodium dispersion. Frequently, however, if

a solvent fractionation step is not inconvenient, a lowerboilinghydrocarbon such as hexane is used, to facilitate separation later. Anyinert aliphatic or cycloaliphatic hydrocarbon is satisfactory.

The olefin is metallated by use of an alkyl sodium which is prepared insitu from an alkyl halide having from about three to about ten carbonatoms. Butyl chloride is preferred, but amyl chloride, hexyl chloride,hexyl bromide, heptyl chloride, amyl bromide, and octyl chloride canalso be used.

The reaction will proceed at low temperatures, which is advantageouswhen the olefin is a gas, such as propylene. A temperature from about-20 C. to about 130 C. can be employed. From one-half to about fivehours reaction time is normally adequate.

The reaction mixture can be prepared by mixing the catalyst diluent,sodium dispersion and alkyl halide, and then adding the alcohol. Afterthe alkoxide has been formed, the olefin is added, and metallated.Excess olefin may be removed, and the residue can be used as the alfincatalyst, without further treatment or purification. In this method, thesodium is first converted to the alkyl sodium, and half of this is thenconverted to the alkoxide, while the remainder is converted to alkenylsodium.

It is also possible to add the alcohol to the sodium dispersion mixedwith the catalyst diluent, forming the sodium alkoxide, and then addingthe alkyl halide, and, finally, the olefin. This procedure requires halfthe amount of alkyl halide, and three-quarters the amount of sodium,required by the first procedure, and is therefore preferred in acommercial operation.

THE MOLECULAR WEIGHT MODERATOR The moderator employed for molecularweight control is a dihydro derivative of an aromatic hydrocarbon, asdescribed in the Greenberg et al. Patent No. 3,067,187.

The dihydro derivatives of aromatic hydrocarbons as embodied hereininclude 1,4-dihydrobenzene, 1,4-dihydronaphthalene, 1,2-dihydrobenzene,1,4'dihydrotoluene, p- 1,4-dihydroxylene, allyl benzene,l-allyl-naphthalene, 1,2- dimethoxy-4-allyl benzene,l-methoxy-l,4-dihydrobenzene, and 1-ethoxy-1,4-dihydrobenzene;4-allyl-toluene, 4-allyl anisole, 4-allyl-diphenyl, 1,4-diallyl benzene,chlorobenzene, bromobenzene, iodobenzene, 1-bromonaphthalene, and thelike, and mixtures of these. 1,4-dihydrobenzene and1,4-dihydronaphthalene are preferred.

The amount of moderator controls the molecular weight, and the amountrequired is dependent upon such factors as the temperature and pressureof the reaction and the quantity and type of diluents employed. Ingeneral, it may vary from about 0.1 to about 10%, based on the weight ofthe monomer, and in the case of the preferred moderators the use ofabout 0.4 to about 1 percent is preferred.

In the practice of the invention, the process conditions, i.e.,temperature, time, catalyst and catalyst concentration, are fixed, andthe molecular Weight is controlled simply by adjustment of theproportion of molecular weight moderator. Thus, complete molecularweight control is obtained by change in only one variable, and that aneasily controlled one. The result is a process that is closelycontrollable within surprisingly narrow tolerance limits.

Although the mechanism of the action of these moderators in molecularweight control is not yet fully understood, carbon-14 studies have shownthat at least one molecule of the moderator is present for each polymerchain, the additional aromatic ring being present presumably as aterminal group. These moderators do not change the ratio of 1,4-trans to1,2-isomers in the resultant polymers, the ratio in the range of 2 to 3in normal alfin rubbers being retained.

THE ALFIN MONOMER THE ALFIN POLYMERIZATION REACTION Before employing amonomer in accordance with the invention, it is essential that themonomer be prepared for the alfin polymerization by removing any Waterthat may be present and usually at least part if not all of anypolymerization inhibitor, particularly any phenols, such as tertiarybutyl catechol, since these materials may destroy the alfin catalyst.First, the water is removed from the monomers, such as in a distillationdryer. 1f the drying tower is operated at 75 p.s.i.g., cooling water maybe used for condensation of both the monomers and the water. The Watercan then be separated from the hydrocarbon monomer layer, which isrecycled to the column. The almost dry monomers can be withdrawn fromthe dryer as a vapor, and condensed again. The monomers are nowessentially dry and contain 20 p.p.m. of water or less, together with afew ppm. of the inhibitor, tertiary butyl catechol, for example. Themonomer can then be withdrawn, leaving behind the inhibitor, which isessentially nonvolatile relative to the monomer, and is ready forfeeding to the polymerization reactor system.

The polymerization is effected in the presence of a hydrocarbon diluentor solvent for the monomer, and the alfin rubber, and that is inert in:the reaction. Preferred reaction media are inert aliphatic andcycloaliphatic hydrocarbons, such as pentane, hexane, a 1:1 mixture ofhexane and pentane, octane, cyclohexane, cyclopentane, cycloheptane,Decalin, and heptane. The preferred reaction solvent is the samehydrocarbon employed for the dispersion of sodium in the preparation ofthe alfin catalysts, such as odorless mineral spiirts or ISOPAR E, orcommercial hexane or isooctane. Branched chain hydrocarbon solvents tendto give polymers having a lower visocsity than straight chainhydrocarbon solvents, and in many cases, consequently, branched chainhydrocarbon solvents are preferred.

The reaction is carried out at an elevated temperature in contrast tothe batch-wise type of reaction described in the Greenberg et al.patent, which employs room temperature or below. Whereas in theGreenberg et al. process the reactants are mixed at a very lowtemperature, of the order of -l C., all of the streams of reactants,including catalyst, molecular weight moderator and diluent or solvent,are blended in the continuous operation of the invention at atemperature within the range from about 40 to about 200 F so as toexpedite a rapid attainment of the reaction temperature, in order tofacilitate heat removal during the initial stages of the reaction.

The polymerization reaction is carried out in a reaction zone, with theblend of reactants continuously entering at one end, and alfin polymerreaction mixture continuously being withdrawn at another end. The rateof transit through the zone is timed to allow polymerization to proceedat least to 70% of completion at the moderator level employed. Thisusually requires from about two to about five hours. The polymerizationtemperature is 40 F. or above, up to approximately 200 F., andpreferably within the range from about 120 to about 180 F.

The reaction is exothermic, and after the selected reaction temperatureis reached, and reaction is proceeding, the reaction temperature shouldbe controlled by removal of heat liberated in the course of thepolymerization. For this purpose, efficient cooling may be needed, witha large surface area exposed to the coolant. The reactors used areprovided with coolant systems, such as jackets and cooling coils,through which a coolant can be circulated, such as water.

For more effective control of reaction temperature and hence of thepolymerization, a series of reactors can be used. The reactors areoperated liquid full, and under pressure, in order to ensure that thereaction is carried out in the liquid phase, in solution or dispersionin the solvent employed. Pressures of from about 1 to about 50atmospheres are suitable, and higher pressures, up to 300 atmospheres,can be used.

Another important feature of the polymerization is the use of arelatively dilute solution of the reactants. In the batch-wise reactionof the Greenberg et al., patent, for example, a 30% butadiene solutionis employed in hexane in Example 1, and a 96% yield of polybutadiene wasobtained in this system. On the other hand, in the continuous operationof the process, the effluent from the polymerization reaction systemshould contain a maximum of 25 weight percent of alfin rubber andpreferably from about 8 to about 15 weight percent alfin rubber at thereaction temperature, before solvent removal. As little as weightpercent alfin rubber is satisfactory and even 2% can be handled, but ofcourse as the solution becomes more dilute the volumes of solvent beingcycled become rather large for the weight of polymer being produced, andefliciency goes down. The olefin and/ or diene monomer starting materialconcentration is adjusted accordingly, and is also at most 25 weightpercent, and preferably from about 8 to about 15 weight percent. 3

The amount of alfin catalyst (solids basis) that is ployed is normallyfrom about 1 to about 6 weight percent, and preferably from about 1 toabout 3.5 weight percent based on theweight of the unsaturatedorganiccompound. I j

As indicated previously, it is quite important that water be excludedfrom the alfin polymerization reaction mixture, and consequently it isessential that all components that are employed therein be anhydrous.

The polymerization reaction is carried out under such conditions thatapproximately to of the diene and/or olefin monomers entering ispolymerized. It is not desirable to obtain a maximum polymerization ofthe olefin and/or diene starting material, unlike a batchwise operation.Control of molecular weight and hence of Mooney of the polymer iseffected by the amount of the molecular weight moderator that is added.The polymerization product is obtained as a solution in the solvent ofthe alfin rubber, and this solution of the alfin rubber is referred toas alfin rubber cement.

At the conclusion of the polymerization reaction, an antioxidant can beadded, as a preservative for the alfin rubber during subsequentprocessing. A very small amount of the antioxidant will be effective. Anamount within the range from about 0.1 to about 5% by weight of thealfin polymer will sufiice. As the antioxidant, there can be employedany organic phenol, organic amine, or arninophenol, such as, forexample, 2,2-methylene-bis(4- methyl-6-tertiary-butyl-phenyl) orN-phenyl-Z-naphthylamine.

The moderator is used in an amount to give the desired molecular weight.It has been determined that after the desired molecular weight isreached in the continuous process of the invention, it is quiteunnecessary to arrest the polymerization. The moderator gives sufiicientprotection. Infact, to add compound such as ethanol for the purpose isundesirable, because this will contaminate the solvent system, and sinceit can poison the alfin catalyst it must be removed before the solventcan be recycled.

TREATMENT WITH ORGANIC ESTER The purpose of the organic ester is toremove the corresponding acetylenes, cyclopentadiene, and otherimpurities that are present in the alfin polymer reaction mixtures asorganosodium compounds. Such compounds undergo substitution reactionswith the ester, and are thereby converted into the correspondingacetylenic and cyclopentadienic alcohols and alcoholates:

R" is the organic radical, such as acetylene or cyclopentadiene, and Rand R are as identified above.

The substitution reactions proceed at the same temperatures at whichalfin monomer polymerization proceeds, so the organic ester can simplybe brought into the reaction mixture at the conclusion of thepolymerization. There is no need to change the temperature of thereaction mixture preparatory to this reaction. Any temperature withinthe range from about 40 to about 300-F. can be used.

Since very small amounts of such impurities are present, and thereaction is stoichiometric, mole for mole, it is not necessary to addmuch organic ester. Usually, from about 0.5 to about 15 weight percent,based on the alfin monomer used, is sufficient. However, an excess doesno harm, and may ensure that all of the small amounts of organosodiumcompounds present are reacted.

The organic ester may also react with unreacted (excess) alfin catalystand with sodium sites on the alfin 1 1 polymer, substituting organicgroups there. However, the latter substituents will be present in minoramounts, if at all, and do not affect polymer properties deleteriously.After the organic ester treatment, the solvent and any unreacted monomerare removed. A preliminary flash step can be used, if desired.

FLASH REMOVAL OF ALFIN MONOMER AND SOLVENT The purpose of the monomerand solvent removal in this step is to recover as much as possible ofthe monomer and solvent by flashing for reuse, and at the same timeconcentrate the alfin rubber cement, while retaining a cement of aworkable viscosity that can be conveyed to the next operation. Usually,a solution containing 14 weight percent or more of alfin polymer is theobjective. Depending on the Mooney value, and the concentration, analfin polymer may contain as much as 26 to 30 weight percent, polymerand still be cement. It is also necessary to free the solvent solutionof any unreacted monomer.

Accordingly, in this embodiment of the process of the invention, monomerand solvent are removed at this stage, by flashing at the conclusion ofthe polymerization, before the alfin catalyst is hydrolyzed by water.Any sodium acid salts present due to the alkylation remain in thereaction mixture during the flashing, while any excess organic ester,and any acetylenic and cyclopentadienic alcohols may be removed at thisstage, if they are sufliciently low boiling.

In the process of the invention, the solvent and monomer are removed byflashing, preferably in several stages. It is more economical to removethe solvent and monomer step-wise, rather than all at once.

In order to effect flash removal of as much of the solvent or diluent aspossible, the first step is to bring the reaction mixture, if necessary,to an elevated temperature at or above the flash temperature at theflash pressure, such as atmospheric pressure. This can be the reactiontemperature, in which case no special heating is necessary. In order toremove the solvent or diluent quickly, however, it is desirable to haveit at as high a temperature as possible, and it may therefore bedesirable to heat the reaction mixture to a higher temperature than theflash temperature.

The flash temperature is the boiling point of the solvent or diluent ata given flash pressure. The maximum flash temperature is thedecomposition temperature of the solvent or diluent, or the polymer.Normally, alfin rubbers do not decompose at temperatures up to 225 C.,and some are stable up to 275 C. Satisfactory flash temperatures foralfin polymers may range from about to about 275 C., depending upon thepolymer and the solvent or diluent.

The pressure that is applied while the mixture is being heated to theflash temperature is sufl'icient to maintain the solvent in the liquidphase until flashing is desired. The pressure may be upwards of 15p.s.i., and frequently is in excess of 100 p.s.i. There is no upperlimit, but usually 500 p.s.i. is suflicient.

The reaction mixture can be brought to any desired flash temperatureunder pressure by passingit through a high temperature electric heateror heating coil. A plate or tube type heat exchanger also can be used,if desired.

Flashing is effected in a flash separator, in which the pressure of thereaction mixture is very quickly reduced to a pressure at which thesolvent flashes off. Atmospheric pressure can be used, as well assubatmospheric pressures down to as low as about atmosphere, dependingupon the solvent and the temperature of the reaction mixture.

Flashing removes as much as possible of the solvent usually from 10 to90% or more and appreciable quantities, if not all, of the monomer. Theresidual solvent is removed by steam distillation, in the presence ofwater. The use of steam permits removal of all of the solvent andmonomer, if a flash step is not desired.

Water washing also extracts any salts formed by the reaction withorganic ester. Such salts are not volatile during the flashing, and areretained in the reaction mixture until extracted by water.

In this step, whether or not a flash step is used prior thereto, thealfin polymer is recovered as crumb from the reaction mixture, and anyremaining volatile materials including any acetylenic andcyclopentadienic alcohols are removed by steam stripping andasimultaneous flashing due to the heat of the steam. Since they arepresent in only very small amounts, and are not deleterious, anynonvolatile compounds can be left with the rubber. The operation iscarried out continuously in the presence of hot water, and any sodiumacid salts are extracted into the water phase. Volatile low polymer isalso stripped. The alfin catalyst that has not reacted with the organicester or the polymer is hydrolyzed, and any olefin and alcohol releasedtherefrom are removed as well, at this stage.

As the first stage in the steam stripping, the alfin polymer solventsolution withdrawn at the end of the polymerization zone is blended withhot water. The water is preferably at a temperature above the steamdistillation temperature of the solvent or diluent to be stripped. Thistemperature will also be above the boiling point of volatile monomer,catalyst alcohol and catalyst olefin. The water is held at thistemperature (inasmuch as the alfin polymer reaction solution iscontinuously being blended therewith in a crumb former or solventstripper) by injection of steam. Thus, a true steam distillation of thevolatiles is obtained in combination with a very rapid flashing ofvolatiles, due to the heat of the water when the water and reactionsolution are blended. The alfin polymer precipitates from the polymersolution as a wet finely divided crumb, and becomes suspended in thewater in this form.

The amount of water used is enough to form an alfin polymer crumbsuspension containing from about 2 to about 10 weight percent crumb. Themaximum crumb content is determined by the handling properties of thesuspension.

The alfin polymer reaction solution is blended with the hot watercontinuously, and the volatiles are continuously drawn off overheadwhile the alfin rubber crumb that becomes suspended in the water iscontinuously separated by screening or centrifuging. The solution can beblended with the water at one end of this zone, and the crumb removed atanother end. One or several stages can be used, depending on equipmentlimitations. Conventional crumb formers or solvent strippers as used inthe synthetic rubber industry are suitable. To aid in stabilizing thesuspension, surface active agent can be added.

The suspension of cement in water simultaneously is subjected to steamstripping. Steam distillation is elfected at a temperature within therange from about 50 to about 130 C. as a result of which the suspensioncan be brought to the boiling point of water. Any volatiles that are notflashed off are steam distilled out.

The steam stripping step is normally carried out under atmosphericpressure. However, it may be desirable to employ sub or superatmospheric pressures, in order to achieve lower or higher strippingtemperatures, and good crumb formation.

The time required to remove all volatiles depends to some extent on theamount and type of volatiles and the physical characteristics of thealfin polymer being processed. Usually, from about 2 to about minutesare adequate. For example, an alfin copolymer of butadiene and styrene,containing from about 75 to about 98 weight percent of butadiene, can berecovered from solution in hexane wherein the polymer concentration isabout 10%, as an essentially solvent-free rubber crumb, that is,containing less than about 0.5% hexane, by steam stripping at 13 atemperature of from about 200 to about 210 F. for about 3 minutes to ahalf-hour.

If desired, as an alternative procedure, and especially When flashing isnot used, the alfin polymer reaction solution can first be subjected toa continuous Water-washing treatment, preferably passing the reactionsolution and the Wash Water countercurrently to each other, therebyremoving isopropanol and Water-soluble salts, and facilitating theproduction of a polymer having an extremely low ash content. The washingstep is not necessary, in most cases, however. If it is used, it can becarried out by passing the alfin polymer solution and water concurrentlyand passing the wet polymer solution to a separation zone, where theWater separates out as an aqueous phase, leaving the alfin polymersolution. The alfin polymer solution is then passed to the steamstripping zone.

IIn a variation of the washing step, in order to ensure a substantiallycomplete removal of water-soluble impurities from the polymer-solventsolution, a two stage of plural stage countercurrent washing can beused.

The volatiles overhead, including monomer, solvent, alcohol, olefin,moderator, and any acetylenic and cyclopentadienic alcohols and water,are drawn oif together. The solvent is separated from the monomer,alcohols, and olefin by the usual condensation and fractionationtechniques, and recycled to the polymerization stage. The monomer can berecovered and recycled, if desired. All are dried before recycling.

CRU'MB SEPARATION AND FINISHING The purpose of this treatment is to drythe alfin rubber crumb, which at this stage may still contain smallamounts of the solvent, molecular weight modifier, and any relativelynonvolatile monomer, such as styrene, and other nonvolatile organiccompounds.

The rubber crumb is first separated by running the suspension through ascreen. The use of cold Water as a Wash for the crumb cake will cool thecrumb, and prevent its sticking to the screen. The Water wash may alsoleach out any residual Water-soluble salts present in the crumb. Thealfin polymer crumb from the screen may then be brought to an expeller,which by means of screw compression reduces the Water content to belowThe remaining water and any solvent can be removed by flashing,compressing the rubber in an expander, so as to heat it, and thenreleasing the pressure suddenly so that Water as steam and solvent flashoff. The water is separated, and some is recycled, while some is purged,since this wash water contains salts and build up of salts must beavoided. The final product from the expander can be baled, and is readyfor distribution and/or use.

THE CONTINUOUS SYSTEM OF FIG. 1

FIG. 1 shows a system in which the continuous process for preparingalfin rubber in accordance with the invention is carried out in theproduction of alfin rubbers from butadiene, isoprene and styrene,separately or in any combination.

The synthesis of the alfin catalyst in this system takes place in ZoneA. The process shown employs sodium, which is prepared as a dispersionin a liquid diluent at a 25 to 50 Weight percent sodium concentration.The sodium dispersion is fed via pump 1 to the storage tank 2 where itis stored under nitrogen. Diluent enters via line 3 and sodium (molten)via line 4 into the mixing tank 5, whence it is circulated via line 7 toa Gaulin mill 8 to reduce the particle size of the sodium, and then backvia line 9 to the mixing tank, to provide an intimate dispersion ofsodium of a particle size of less than 10 microns average diameter inthe diluent. The finished dispersion is bled off continuously via line10 to one of two storage tanks 11, 12, equipped with agitators tomaintain uniformity.

To prepare the alfin catalyst, a batch technique is used. Diluent fromstorage 14 is charged via line 15 to the catalyst synthesis reactor 16,an agitated vessel equipped with cooling facilities. Sodium dispersionis added via line 15 from tanks 11 or 12, and isopropyl alcohol isgradually added from storage 17, via line 18 'with agitation and coolingat a temperature of approximately 0 to C. Since the reaction isexothermic, the alcohol addition is slow. In this way, one-third of thesodium is converted to sodium isopropoxide. The addition of butylchloride from storage 19 via line 18 then converts most of the remainingsodium in the tank 16 equimolar quantities of sodium butyl and sodiumchloride. This also is an exothermic reaction and cooling is required.The temperature is held within the range from about 0 to about 80 C.

After the addition of butyl chloride is complete, the reaction isallowed to proceed to completion, with agitation. @Propylene fromstorage 20 is then added directly via line 18 to the liquid contents ofthe vessel. This addition converts sodium butyl to sodium allyl, withthe formation of butane as a by-product. Very little heat is evolved atthis point, and the reactor is kept under the pressure of the propylenesolution. The pressure at this point should be less than 40 p.s.i.g. Thecontents of the reactor are held at this temperature for several hours,and the pressure then reduced to atmospheric by venting. Butane andexcess propylene may be partially removed by heating. The contents thenare transferred to one of two catalyst storage tanks 21, 22.

The catalyst preparation can be converted to a continuous operation byproviding three catalyst reactors in series, in which each step of thecatalyst preparation is carried out in sequence.

Catalyst suspension is supplied to the polymerizers continuously fromone of tanks 21, 22 via line 23. The tanks are equipped with agitatorsto avoid settling of the solids.

The alfin monomer polymerization process takes place in Zone B. Theprocess will be described for preparing a butadiene-isoprene rubber.Monomer feed is prepared for use in the polymerization by removing Waterand any inhibitor in the strippers 24, 26 from butadiene and iso-'prene, since these substances destroy catalyst. The preparation of abutadiene-styrene rubber is similar, except that only the butadiene isdried. The dry monomers are fed via lines 25, 33 to the firstpolymerization reactor 31. Dry moderator is stored in tank 27.

A plurality of polymerizer reactors 31, connected in series, in thiscase, three, is used. These are each jacketed, and contain coolingcoils. The coolant is water, or other suitable liquid. The reactiontemperature is within the range from about to 200 F. All polymerizersare operated liquid-full.

The maximum polymerization pressure is that needed to ensure adequatepressure containment in the event of an upset, and also to ensuresufiicient pressure for the reactor effluent to flow to the alfin cementblend and feed tanks.

The polymerization is carried out by passing recycle stream 30consisting essentially of iso-octane and some recycled butane andbutadiene to the first of the three polymerizer reactors 31, 31' (onlytwo are shown). Dry moderator from tank 27 and fresh dry monomer in line33 are mixed with the recycle in the desired proportions and chargedtogether to the polymerizer. Catalyst via line 23 is injectedseparately. Since the reaction is exothermic, heat must be removed.

The polymerizer efiiuent from the last reactor, while still at reactiontemperature, is then run via line 37 to the organic ester reaction tank38, where it is reacted with organic ester and also blended with alfincement to the desired Mooney value, if necessary. Organic ester isadmitted via line 38a in the proportion needed, and the mixture held inthe tank for a suflicient time to permit reaction to become complete.From a half hour to several hours is adequate.

Reaction with the organic ester can also be effected in the concentratorfeed tank 39. Organic ester is admitted via line 39a. Also, organicester can be added to the alfin cement in line 37, and reaction thentakes place in course of. transit in the line and in the tanks 38 and/or 39.

During normal operation, when product of the proper Mooney is beingmade, the flow will be directly to the feed tank 39. Blending to thedesired Mooney level can be obtained by mixing alfin cement from variousstorage tanks in the blend tank 38. Both tanks 38 and 39 are kept underan inert atmosphere. The stirring and agitation therein ensure thoroughmixing and complete alkylation.

Alfin cement of the desired Mooney is charged from the tanks 38 and/or39 via line 34 to the first of three flash stages of concentration inZone C. A first stage heater 32 is provided in the line 34, in the eventthat the alfin cement stream is below flash temperature. In addition, aspare flash heater servicing the entire concentration system can beprovided in a recycle line connected to the flashers.

The concentration system is composed of three flashers 35, 35, 35", andthese are operated so that no vaporization takes place in the tubes ofthe heaters 32, 32, 32". This is effected by maintaining a pressure onthe discharge of the heaters greater than the boiling point of thesolution, preferably higher than the maximum skin temperature ofl thetubes. Here, steam condensing at a temperature of 350 is used.

The effiuent from the first stage heater is at approximately 200 to 275F., and 50 to 110 p.s.i.g. and flashes in 35 by reduction of pressure to1 p.s.i.g. The vapor stream is withdrawn through line 46, and the liquidstream is also withdrawn in line 36, and charged to the inlet of thesecond stage heater 32'. The rubber cement now contains, for example,9.8 weight percent of alfin rubber. It issues from the heater atapproximately 210 to 275 F. and 80 to 100 p.s.i.g. and flows into 35',the second stage flash tank, which is maintained at approximately 1p.s.i.g. The temperature after flash at this point is approximately 150to 230 F. The vapor stream is separated and withdrawn via line 46. Theliquid from the flash tank 35 containing, for example, approximately11.5 weight percent of alfin rubber is withdrawn via line 36" and ischarged to the third stage heater 32". After these two stages ofconcentration, most of the butadiene and the isoprene remainingunreacted has been removed as vapor.

The liquid eifluent from the third stage heater 32. at approximately 150to 275 F. and 60 to 100 p.s.i.g. flows to the third stage flash andsurge tank 35", wherein the liquid flashes upon pressure reduction, andthe vapor stream at approximately 180 to 230 F. and 1 p.s.i.g. iswithdrawn to line 46. This vessel provides surge capacity for rubbercement of approximately a 15 weight percent alfin rubber concentration.The liquid cement is withdrawn via line 40 and is then charged to thefirst stage of the crumb formers 41, 41. Approximately one-half of thetotal solvent has been removed at this stage by evaporation, andsubstantially all of the butadiene and is prene have been recovered.

taining approximately 12 to weight percent rubber is continuouslycharged via line 40 to the first of two solvent strippers 41, 41'. It ismixed with hot recycled water entering via line 47 so that a suspensionof alfin cement in water results. I f desired, dilute solution ofemulsifying agent from storage 44 can be added via line 45. Theresultant mixture enters the first solvent stripper 41, a vesselequipped with a stirrer and overhead collection line 42 running to acondenser. The water is hot enough to flash some of the solvent. Steamand solvent vapors from 41' are injected via line 49c to eflect a steamdistillation, and heat the mixture to a temperature of about to about130 C., while the mixture is stirred. Solvent vapors escape via line 42.A slurry of alfin rubber crumb results, and the rubber slurry is removedfrom below and is sent via line 48 to the second stage solvent stripper41', which is similar to the first stage. Most of the solvent is removedin the first stage, and the rubber entering the second stage has forexample a solvent content of the order of 5 to 10 weight percent, basedon the alfin rubber content.

Stripper 41 operates at a temperature of approximately 212 F. Steam isalso injected directly into this vessel via lines 49a and b. An aqueousslurry of alfin rubber of the order of 2 to 6 weight percent rubber iswithdrawn via line 50. The solvent content of the rubber at this pointis of the order of 1 weight percent, based on the alfin rubber.

The product vapor stream in line 42 contains essentially all thehydrocarbons that were present with the exception of the rubber. Inaddition, it contains propylene, formed by decomposition of the catalystwith water to form sodium hydroxide. It also contains isopropyl alcohol,formed by hydrolysis of the sodium isopropoxide, along with any excessvolatile organic ester. The rubber crumb contains small quantities ofthe moderator dihydronaphthalene, styrene (if present), as well as asmall amount of solvent. The quantity of solvent in the crumb at thisstage should be kept to a minimum by appropriate adjustment of the steamstripping conditions.

The slurry from line 50 enters a separator 51 equipped with a mechanicalrake 52, so that rubber crumb which floats to the surface of this vesselcan be skimmed off. The water in the lower portion of this vessel,relatively free of rubber crumb, is recycled to stripper 41 via lines53, 54, 47. In addition, to prevent buildup of salts, a proportion ispurged, and replaced by make-up water which enters at line 54.

The rubber crumb which is present in the form of small particles andcontains substantial water and which is raked out enters a dewateringscreen separator 55 via a chute 56. In the chute, the rubber crumb iscontacted with a stream of cold water which cools the crumb. Theunderflow from the screen consists essentially of water containing asmall amount of rubber fines, and is withdrawn and pumped to a secondaryfines settler '58. Rubber crumb is allowed to overflow from the upperportion of this vessel, and passes via line 59 back on to the screenseparator 55. The underflow consists of water containing dissolvedsalts, and is purged.

The alfin rubber crumb discharged from the separator 55 is fed byconveyor 60 to an expeller 61. The expeller by means of screwcompression reduces the water content to approximately 9 Weight percent.The water discharged from the expeller is returned to the fines settler58 via line 62. The rubber from the expeller passes through line 63 andenters an expander 64. Here, .by compression, and jacket-heating, therubber is heated, so that upon discharge water as steam and solventflash ofli. A stream of hot purge air to carry away water vapors and anysolvent to prevent condensation in the crumb is provided by blowers 65.The alfin rubber at this point in the form of crumb is conveyed to acrumb conveyor and cooler 66 and subsequently to a baler 67 where it canbe packaged in pound bales. These are conveyed via conveyer 69 tostorage. The solvent and other volatiles removed at the expander arevented.

The solvent recovery and purification system shown in Zone E is designedto (1) recover solvent and optionally monomer, (2) to purge the systemof essentially all the alcohol and part of the butane and propylene and(3) to remove heavy ends such as acetylenic and cyclopentatower 76 andremoved as an overhead stream via line 77;

The dry liquid bottoms, consisting of solvent and most of the monomers,is recycled via line 30 to solvent storage 73, and thence vialine 74 tothe polymerizers.

Wet solvent vapors in line 42, along with isopropyl alcohol andpropylene, are condensed in condenser 80, decanted in decanter 81, andthe alcohol-water layer removed at the bottom of the decanter via line82. The wet liquid hydrocarbon layer is sent to the butylene removaltower 83, where the propylene, water, and remaining isopropyl alcoholare removed overhead in line 84 by distillation. The bottoms are sentvia line 85 to a heavy ends tower '86, wherein wet purified solvent istaken overhead in line 87 and recycled to the process via dryer 71 andline 30. The bottoms (the heavy ends including the acetylenic andcyclopentadienic alcohols, and unreacted ester) are rejected. If styreneis present, it can be recovered from the heavy ends.

THE CONTINUOUS SYSTEM OF FIGURE 2 FIGURE 2 shows a modified system inwhich the flash step is omitted.

The 'synthesis'of the alfin catalyst in this system takes place in ZoneA. The process shown employs sodium, which is prepared as a dispersionin a liquid diluent at a 25 to 50 weight percent sodium concentration.The molten sodium is fed via pump 101 to the storage tank 102 where itis stored under nitrogen. Diluent enters via line 103 and sodium(molten) via line 104 into the mixing tank 105, whence it is circulatedvia line 107 to a Gaulin mill 108 to reduce the particle size of thesodium, and then back via line 109 to the mixing tank, to provide anintimate dispersion of sodium of a particle size of less than 10 micronsaverage diameter in the diluent. The finished dispersion is bled oifcontinuously via line 110 to one of two storage tanks 111, 112, equippedwith agitators to maintain uniformity.

To prepare the alfin catalyst, a batch technique is used. Diluent fromstorage 114 is charged via line 115 to the catalyst synthesis reactor116, an agitated vessel equipped With cooling facilities. Sodiumdispersion is added via line 115 from tanks 111 or 112, and isopropylalcohol is gradually added from storage 117, via line 118 with agitationand cooling at a temperature of approximately to 80 C. Since thereaction is exothermic, the alcohol addition is slow. In this way,one-third of the sodium is converted to sodium isopropoxide. Theaddition of butyl chloride from storage 119 via line 118 then convertsmost of the'remaining sodium in the tank 116 to equimolar quantities ofsodium butyl and sodium chloride. This also is an exothermic reactionand cooling is required. The temperature is held within the range fromabout 0 to about 80 C.

After the addition of butyl chloride is complete, the reaction isallowed to proceed to completion, with agitation. Propylene from storage120 is then added directly via line 118 to the liquid contents of thevessel. This addition converts sodium butyl to sodium allyl, with theformation of butane as a by-product. Very little heat is evolved at thispoint, and the reactor is kept under the pressure of the propylenesolution. The pressure at this point should be less than 40 'p.s.i.g.The contents of the reactor are held at this temperature for severalhours,

and the pressure then reduced to atmospheric by'venting.

Butane and excess propylene may be partially removed by heating. Thecontents then are transferred to one of.

two catalyst storage tanks 121, 122. Each storage tank holdsapproximately a one day supply of catalyst for use in the continuousprocess of the invention.

The catalyst preparation can be converted to a continuous operation byproviding three catalyst reactors in series, in which each step of thecatalyst preparation is carried out insequence.

' Catalyst suspension is supplied to the polymerizers continuously fromone of tanks 121,122 via line 123. The tanks are equipped with agitatorsto avoid settling of the solids. I

The alfin monomer polymerization process takes place in Zone B. Theprocess will be described for preparing a butadiene-isoprene rubber.Monomer feed is prepared for use in the polymerization by removing waterand any inhibitor in the strippers 124, 126 from butadiene and isoprene,since these substances destroy catalyst. The prep-' aration of abutadiene-styrene rubber is similar, except that only the butadiene isdried. The dry monomers are fed via lines 125, 133 to the firstpolymerization reactor 131. Dry moderator is stored in tank 127.

A plurality of polymerizer reactors 131, connected in series, in thiscase, three, is normally used. These are eachjacketed, and containcooling coils. The coolant is water, or other suitable liquid. Thereaction temperature is within the range from about to 200 F. Allpolymerizers are operated liquid full.

The maximum polymerization pressure is that needed to ensure adequatepressure containment in the event of an upset, and also to ensuresufficient pressure for the reactor efiluent to fiow to the alfin cementblend and feed tanks.

The polymerization is carried out by passing recycle stream 130consisting essentially of iso-octane and some recycled butane andbutadiene to the first of the three polymerizer reactor 131, 131' (onlytwo are shown). Dry moderator from tank 127 and fresh dry monomer vialine 133 are mixed with the recycle in the desired proportions andcharged together to the polymerizer. Catalyst is injected separatelythrough pipe 123. Since the reaction is exothermic, heat must beremoved.

The polymerizer efiiuent from the last reactor 131 while still atreaction temperature flows via line 137 to either the alfin cement blendtank 138 or to the concentrator feed tank 139.

During normal operation, when product of the proper Mooney is beingmade, the flow will be directly to the feed tank 139. Blending to thedesired Mooney level can be obtained by mixing alfin cement from variousstorage tanks in the blend tank 138.

Reaction with the organic ester is effected at this temperature ineither of tanks 138 and 139. Organic ester is admitted via lines 138aand 139a, and both tanks are kept under an inert atmosphere, withthorough mixing, to ensure complete reaction.

Alfin cement of the desired Mooney is fed via line 140 to the firstsolvent strippers or crumb formers 141, 141'. Approximately 95% of thetotal solvent is removed in the first solvent stripper, andsubstantially all of the residual unreacted butadiene and isoprene arerecovered. The combined vapor stream from the solvent strippers flows toa condenser and purification system in Zone D and the solvent isrecycled.

The crumb formation and finishing operations take place in Zone C. Theseare the same whether an isoprene or styrene rubber is made. The isoprenerubber case is described.

Rubber cement for example containing approximately 8 to 25 weightpercent rubber is continuously charged to the first of two solventstrippers 141,,141'. It is mixed with hot recycled water enteringvialine 147 so that a suspension of alfin cement in water results'withthe alcohols or alcoholates from the organic ester reaction beingextracted into the water. If desired, a dilute solution of emulsifyingagent from storage 144 can be added via line 145. The resultant mixtureenters the solvent stripper 141, a vessel equipped with a stirrer andoverhead collection line 142 running to a condenser 143. The water ishot enough to flash some of the solvent. Steam and solvent vapors areinjected from 141' via line 1490 to effect a steam distillation, andheating the mixture to a temperature of about 205 F., while the mixtureis stirred. Solvent vapors escape via line 142. A slurry of alfin rubbercrumb results, and the rubber slurry is removed from below via line 148and is sent to the second stage solvent stripper 141', which is similarto the first stage. Most'of the solvent is removed in the first stage,and the rubber entering the second stage has for example a solventcontent of the order of to weight percent, based on the alfin rubbercontent.

The product vapor stream in line 142 contains BSSCH? tially all theremaining volatile hydrocarbons that were present. In addition, itcontains propylene, formed by decomposition of the catalyst with waterto form sodium hydroxide. It also contains isopropyl alcohol, formed byhydrolysis of the sodium isopropoxide, along with acetylenic andcyclopentadienic alcohols and any excess organic ester used. The rubbercrumb contains small quantities of the moderator dihydronaphthalene,styrene (if present) as well as a small amount of solvent, and may alsocontain a trace of any nonvolatile organic ester. The quantity ofsolvent in the crumb at this stage should be kept to a minimum byappropriate adjustment of the steam stripping conditions.

The slurry from line 150 enters a separator 151 equipped with amechanical rake 152, so that rubber crumb which fioats to the surface ofthis vessel can be skimmed oil. The water in the lower portion of thisvessel, relatively free of rubber crumb, is recycled to stripper 141 vialine 147. In addition, to prevent buildup of salts, a proportion ispurged, and replaced by make-up water which enters at line 154.

The rubber crumb which is present in the form of small particles andcontains substantial water and which is raked out enters a dewateringscreen separator 155 via a chute 156. In the chute, the rubber crumb iscontacted with a stream of cold water which cools the crumb. Theunderflow from the screen consists essentially of water containing asmall amount of rubber fines, and is withdrawn and pumped to a secondaryfines settler 158. Rubber crumb is allowed to overflow from the upperportion of this vessel, and passes via line 159 back on to the screenseparator 155. The underfiow consists of water containing dissolvedsalts, and is purged.

The alfin rubber crumb discharged from the separator 155 is fed byconveyor 160 to an expeller 161. The expeller by means of screwcompression reduces the water content to approximately 9 weight percent.The water discharged from the expeller is returned to the fines settler158, via line 162. The rubber from the expeller passes through line 163and enters an expander 164. Here, by compression, and jacket-heating,the rubber is heated, so that upon discharge water as steam and solventflash oil. A stream of hot purge air to carry away water vapors and anysolvent to prevent condensation in the crumb is provided by blowers 165.The alfin rubber at this point in the form of crumb is conveyed to acrumb conveyor and cooler 166 and subsequently to a baler 167 where itcan be packaged in 75 pound bales. These are conveyed via conveyor 169to storage. The solvent and other volatiles removed at the expander arevented.

The solvent recovery and purification system shown on Zone D is designedto (1) recover solvent and optionally monomer, and (2 topurge the systemof essentially all the alcohol and of part of the butane and propylenefrom the hydrolysis, and (3.) .to remove heavy ends such as acetylenicand cyclopentadienic alcohols, ,and any volatile unreacted organicester. I

The wet solvent vapors in line 142 are condensed, condenser 143, flowedto a decanter 170, from which the alcohol-water layer is removed at thebottom, vialine 171, andthe upper organic layer is charged via line 174to a fractionator tower 175 wherein everything exc'ept a.

small portion of the solvent and heavy ends are taken over head via line176. The overhead is condensed, in condenser 177, and run to decanter178 where the water layer is. removed by decantation along with most ofthe alcohol, which is dissolved in the water. The organic layer,consisting of solvent, unreacted monomer, propylene, butane, and somealcohol, is charged to' washing tOW I 179, and washed with water toremove isopropyl alcohol, which is separated, and. the bottom waterlayer purged. The organic layer after decantation of the water consistsof solvent, butanes, propylene, and volatile monomers. This is run vialine 180 to the tower 181. The overhead is monomer, butane andpropylene, along with some water. Part of this is purged, and theremainder recycled via line 182 to dryer 183, and thence to line 130 andsolvent storage 173. The liquid bottomsfrom tower 181 are dry solvent,with a trace of monomers, and are recycled directly to line 130 via line182.

The bottoms from the tower 175 are charged via line 184 to anotherdistillation column 185 wherein pure solvent is taken overhead via line186, condensed in condenser 188, and recycled via line 182 to dryer 183.The heavy ends, along with any light polymer, and acetylenic alcoholsand impurities, and any unreacted organic ester, are removed from thebottom via line 187, and rejected.

Styrene if present can be recovered from the heavy ends by distillation.

The equipment described can be designed to produce any type of alfinrubber, such as a butadiene isoprene copolymer, or a butadiene styrenecopolymer. The butadiene isoprene copolymer can be approximately weightpercent butadiene and 20weight percent isoprene. The styrene rubber canbe approximately weight percent butadiene, and 15 weight percentstyrene. The rubber has a 30 to Mooney range.

THE CONTINUOUS SYSTEM OF FIG. 3

In the apparatus of FIG. 3, alfin catalyst in the form of a solventslurry, e.g. isooctane slurry, is passed from catalyst feed tank 210through. pump 212 and line 214 to below the surface of the liquid inreactor 216, first of a group of four reactors 216, 227, 228 eachequipped with a stirrer 217. Simultaneously with the addition of thecatalyst to reactor 216, butadiene is distilled from tank 211 through amolecular sieve drier 213 and thence condensed in condenser 215, andpassed into line 218 leading to the V mixing tank 219. Simultaneouslywith this addition, there are also introduced into the mixing tank 219 amolecular weight moderator, e.g., l,4-dihydronaphthalene from feed tank220 through line 221, isoprene or styrene from feed tank 230 throughline 232, and isooctane solvent from tank- 222 via drier 223 throughline 234. In the case of all feeds to tank 219, there are provided inthe feed lines Rotameters 224 to regulate the feed rate of eachcomponent, thus making adjustable the monomer ratio, the molecularweight of the polymer formed and the concentration of polymer insolution.

Reference numeral 240 denotes the jacket surrounding each reactorthrough which water or other coolant may be circulated to maintain thereaction temperature, preferably at about to about F., although higheror lower temperatures, e.g. 40 to 200 F., can be used.

Reaction mixture composed of solvent (isooctane), unreacted monomers,and moderator is passed by gravity from tank 219 through overflow pipe242 to the first reactor 216, where catalyst is added and polymerizationbegins. The reaction mixture passes through overflow pipe 248 to asecond reactor 226, thence via line 249 to the third reactor ,227, andthence via line 250 to the fourth reactor 228. Four reactors' areutilized herein to prov dev adequate retention time for thepolymerization process, and control heat liberated. during the reaction.

The first three reactors are run liquid full.

If desired, the process couldbe conducted in a single:

reactor, designed to give the desired retention time, although 1t 1sbelieved preferable to utilize at least two reactors, to provide foreffective heat removal, to permit 21 more complete reaction, and toobviate the need for recovering unreacted monomers.

The stirrers 217 preferably are of the variable speed, turbine type,whereby speed may be adjusted to give good agitation consistent with theviscosity of the polymer.

Retention time in the four reactors shown may vary considerably,depending upon the nature of the desired polymer. In many cases it hasbeen found that retention time in each reactor of thirty minutes to onehour is entirely suitable, although retention time may be extended to asmuch as six to eight hours per reactor.

Alfin polymer solution while still at reaction temperature is withdrawnfrom the bottom of the last reactor 228 and is fed by pump 254 driven bya variable speed motor (not shown) through line 256 to one of twoalkylation tanks 257. Organic ester is admitted via llne 258 andthoroughly blended with the reaction mixture, which is given a residencetime of from /2 hour to 3 hours in passing through the tank. Thispermits react on with organic ester to proceed to completion. Thereaction mixture is then washed to remove any resulting salts and otherwater-soluble impurities, such as catalyst alcohol, and other salts.

The reaction mixture passes via line 259 to centrifugal wash pump 262,which is employed for the washing operation. Water to be utilized toremove water-soluble salts, isopropanol, and other impurities from thepolymer solution is passed through line 261 and a heat exchanger 260 toline 259 from which it enters the centrifugal wash pump 262 togetherwith polymer solution from the reactors. The temperature of the waterand organic streams may vary over a considerable range, e.g. from 32 F.up to the boiling point of the mixture depending upon the systempressure. However, a system temperature of 120 to 150 F. is preferred.In centrifugal wash pump 262 a temporary emulsion of the water andorganic phases is formed, and thence passed through lme 264 to adecanter 266 where the heavier water phase containing the water-solublesalts, isopropanol, and other impurities is discharged to waste throughline 268, while the lighter organic phase containing the salt-freeproduct is discharged through line 270 to one of two product solutionsurge tanks 272. This process of washing the organic phase with water toremove alcohol and salts may be repeated as often as is nesessary.Numeral 263 denotes a recirculation conduit for recirculating aqueousand organic liquid through the centrifugal wash pump 262. If desired,antioxidant may be added to the product at this stage in the operationthrough line 274.

From surge tanks 272 the polymer solution is fed by pump 276 throughline 278 to a solvent stripper 280.

Hot water and steam are passed into the solvent stripper 280 throughlines 282 and 284, respectively. The operation of the solvent stripperis such as to result 1n continuous vaporization of the solvent by mixingof the polymer solution in hot water while simultaneouslysteam-distilling the solvent, thereby forming a slurry of the polymercrumb in water. In the embodiment shown, the polymer crumb overflows atthe liquid operating level of the solvent stripper 280, which may beadjusted to provide the retention time required to completely remove thesolvent. The crumb is withdrawn through overflow pipe 288 to a screeningoperation.

The crumb-water slurry passing through overflow pipe 288 is sent toproduct screen tank 290 into which wash water is also passed throughline 292. The water is withdrawn from tank 290 via line 296, and part isrecycled to the solvent stripper 280 and part is purged. The washedpolymer crumb is removed from the screen tank 290, and may then bepassed through subsequent stages such as drying, milling and packaging.

The amount of solvent used in the process of the invention isconsiderable, and obviously such quantity of solvent cannot be lost andstill maintain an economically feasible operation. Accordingly, solventdistilled from solvent stripper 280 and containing water is passedthrough line 300 and condenser 302 to the solvent-water separator 304.In this separator the heavier water phase along with any residualisopropyl alcohol settles to the bottom and is passed through line 308to waste, while the solvent liquid is passed through line 310 to storagetank 312 and thence fed by pump 214 to a distillation drying column 316.

The light ends (propylene, butane, butadiene, isoprene and some solvent)are withdrawn overhead via line 320 to a condenser 321, where they arepartially liquefied. These light ends can be partially condensed so thatthe liquid contains most of the monomers and these monomers recycledafter drying. A portion is purged to get rid of propylene and butane.The liquid is run into decanter 323, where the water is separated, andthe liquid is returned via line 324 to the column 316. The solventliquid is withdrawn at the bottom of the column via line 305 and pump307 to the heavy ends removal column 313.

The heavy ends (including acetylenic and cyclopentadienic alcohols, andany unreacted ester) are withdrawn at the bottom of the column, andstyrene if present may be recovered by distillation and recycled; theremainder is discarded. The dry light solvent ends are condensed incondenser 315 and thence led via line 317 to the dry solvent storagetank 318, after which they are recycled to the solvent feed tank 222 vialine 325.

The washing system provides a simple, eflicient and highly flexibleprocess for removing water-soluble components from the organic streamsencountered in the continuous alfin polymerization process of thisinvention. Obviously, where the end use of a polymer is such as not torequire substantial absence of ash, the entire washing operation may beomitted from the process, and polymer solution passed directly from thereactors to the desolventizing operation.

The washing method of this invention achieves intimate contact of theorganic polymer phase with the aqueous phase by feeding of the organicpolymer phase and the aqueous phase into a central zone from which thestreams are centrifugally impelled radically outwardly at high speedagainst a peripheral collection zone surrounding the said central zone.The streams are thus converted to an emulsion by the violent radicallyimpelling force and then delivered as a single stream to a dischargezone, and divided into two portions, one of which is recirculated to thecentral zone for further mixing with fresh feed, while the other portionin emulsion form is passed to a decanting area for separation in themanner described above.

Water is conserved by providing for two or more of the just describedwashing systems in series. In this embodiment the emulsion formed by theradically impelling force in a first zone is divided into two streams,one of which is recirculated to the central zone for further mixing. Thesecond stream is decanted and the partially washed organic phase is usedas the feed for a second stage operation to be intimately contacted withfresh water. The decanted aqueous phase from this second stage is usedas the wash liquid for crude organic phase in the first stage.

In contrast to the prior art polymer washing methods using stirred-tankWashing means and requiring mixing periods of one-half hour to severalhours, the instant washing method requires a mixing time on the order ofseconds. Moreover, in many cases, the present washing method obviatesthe need for catalyst deactivation, polymer precipitation and theaddition of emulsion-breaking agents before decantation, which steps aregenerally required in prior art methods.

The following examples in the opinion of the inventors representpreferred embodiments of their invention.

23 Example 1 A butadiene-isoprene copolymer can be prepared inaccordance with the following procedure, using the apparatus of FIG. 1.

Liquid sodium (194 lbs.) at approximately 250 F. is charged to thesodium dispersion preparation tank 5, and 510 pounds of isooctane run infrom storage 14 via line 3 under suflicient pressure to ensure theexistence of the diluent as a liquid, whereupon the sodium is dispersedtherein at 240 F. via the Gaulin mill 8 to form a uniform dispersion.

An alfin catalyst is prepared by charging 2100 pounds isooctane to thecatalyst synthesis reactor 16, after which 510 pounds of the sodiumdispersion and 120 pounds of isopropyl alcohol are added with agitationand cooling to maintain approximately 150 F. The alcohol is added over athree hour period. Approximately one-third of the sodium is therebyconverted to sodium isopropoxide. Then, over a five hour period 190pounds of butyl chloride is added, converting most of the remainingsodium to ap proximately equimolar quantities of sodium butyl and sodiumchloride. After addition of the butyl chloride is complete, the reactionis completed by stirring for a further hour.

Next, 95 pounds of propylene is added, converting sodium butyl to sodiumallyl, with the formation. of butane as a byproduct. This is retained inthe system.

Catalyst slurry thus prepared is fed to the first polymerizer reactor 31via line 23 at a rate of 130 pounds per hour. Dry butadiene is chargedcontinuously via line 33 at a rate of 480 pounds per hour, and dryisoprene via line 33 at a rate of 120 pounds per hour.1,4-dihydronaphthalene as a dilute solution is added as a moderator at arate of 25 pounds per hour for the total solution. Approximately 6,450pounds per hour of a stream consisting of mostly isooctane withsubstantial quantities of recovered monomers is added. All of thestreams are fed in at approximately 105 F.

The three polymerizers 31, 31 are operated liquid full, and cooled bywater at 85 F., so as to maintain a reaction temperature of 150 to 160F. The pressure in the polymerizers is a maximum of 50 p.s.i.g. Thereaction mixture is fed in sequence from polymerizer to polymerizer, andthe total travel and reaction time through the entire series is aboutthree hours.

The polymerizer eflluent in line 37 contains about 8 Weight percentalfin rubber at 150 F., and is fed at a rate of 21 gallons per minute tothe organic ester reaction and feed tank 39, where organic ester, inthis case, octyl acetate, is admitted at a rate of pounds/hour, beneaththe surface of the liquid in the tank. Residence time in the tank isabout 8 hours, and the temperature of the reaction mixture is aboutIOU-150 F. Eifluent reaction mixture is fed at a rate of 22 gallons perminute through line 34 to the flash concentrators. This amounts to 7,235pounds per hour. The effluent from the heater 32 is at approximately 270F. and 200 p.s.i.g. and is flashed in the first flasher 35 by reductionin pressure to 1 p.s.i.g. Monomer and solvent vapors are withdrawn fromthe flasher 35 at the top via line 46, and the liquid is withdrawn vialine 36 and charged to the second stage heater 32'. This stream containsapproximately 11 weight percent alfin rubber, and is fed from the heaterat 275 F. and 200 p.s.i.g. via line 36 into the second flash tank 35'maintained at approximately 1 p.s.i.g. The temperature after flashing isapproximately 215 F. The vapor stream is separated overhead into line46. The eflluent is Withdrawn via the line 40. The solvent and monomervapors in line 46 are run into the condenser and fractionator system forrecycling after purification.

The polymerizer eifluent in line 40 contains approximately 15 weightpercent alfin rubber at 215 F., and to this is added 10.8 lbs./hr. of anantioxidant solution. This is fed at a rate of 3,785 pounds per hour tothe first solvent and recycled. Butadiene dimer is also. removed, and,is

purged.

An 8 weight percent rubbercrumb in water and is drawn off at the bottomof the stripper via line' 48, and is sent to the second stage solventstripper or crumb former 41', where the steam distillation is repeated.The solvent content of the crumb charged to this stage; is approximately10 weight percent, based on therubber content. The aqueous slurry ofrubber emerging from this crumb former has the solvent content reducedto '1' weight percent based upon the rubber content. The vapor stream inline 42 contains essentially .all of the solvent originally present withthe crumb, except the. acetylenes and cyclopentadienes, and in additionany unreacted pro pylene and isopropyl alcohol formed by hydrolysisofthe catalyst. The rubber crumb contains only small amounts" of molecularweight moderator and solvent.

The crumb slurry from the solvent stripper:41

tacted with a stream of cold water at a rate of approxi-v mately 13gallons per minute. This cools the, crumb. The

underflow consisting of water and a small amount of rubber fines, ispumped to the fines settler 55, where the,

rubber crumb overflows from the upper portion of the vessel back on tothe screen 56. The underflow is purged. The rubber crumb discharged fromthe screen is fed by' the conveyor 60 to the expeller 61, which reducesthe Water content by screw compression from 60% to approximately 9%. Therubber crumb then enters the ex; pander 64 where, by compression, therubber is heated to approximately 300 F., so that upon discharge fromthe expander, water as steam and solvent flashes. off. The product isthen baled in the baler 67, and is,;1 teady fordistribution.

Q Example 2 A butadiene-isoprene copolymer' can beprepared in accordancewith the following procedure, using the 'ap paratus shown in FIG. 2.

Liquid sodium (194 lbs.) at approximately 240 F. is charged to thesodium dispersion preparation tank 105, and 510 pounds of isooctane runin from storage 114 via.

line 103 under a pressure of 35 p.s.i.g., whereupon the sodium isdispersed therein 'at 240 F. via the Gaulin mill- 108 to form a uniformdispersion.

An alfin catalyst is prepared by charging 2100 pounds isooctane to thecatalyst synthesis reactor 116, after which 510 pounds of the sodiumdispersion and pounds ofisopropyl alcohol are added with agitation andcooling to maintain approximately F. The alcohol is added over a threehour period. One-third of the sodium is thereby converted to sodiumisopropoxide. Then, over a five hour period pounds of butyl chloride isadded,

converting most of the remaining sodium to equimolar quantities ofsodium butyl and sodium chloride. After addition of the butyl chlorideis complete, the reaction.

is completed by stirring for a further hour.

Next, 95 pounds of propylene is added, converting sodium butyl to sodiumallyl, with the formation of butane as a by-product. This is retained inthe system.

Catalyst slurry thus prepared is fed to the first reactor 131 via line123 at a rate of 130 pounds per hour. Dry butadiene is chargedcontinuously via lines 124, 133 at a rate of 480 pounds per hour, anddry isoprene via lines 126, 133 amounting to 120 pounds per hour.1,4-dihydronaphthalene is added as a moderator at a rate of 3.5 poundsper hour, and isooctane is added at a rate of 4260 pounds per hour. Allof the streams are fed in at approximately 100 F.

The six reactors 131, 131' are cooled by water at 85 F., so as tomaintain a reaction temperature of 150 to 160 F. in each of thereactors, which are operated liquid full. The pressure in the reactorsis a maximum of 50 p.s.i.g. The reaction mixture is fed in sequence fromreactor to reactor, and the total travel and reaction time through theentire series is about three hours.

The polymerizer eflluent in line 140 contains about 12 weight percentalfin rubber at 150 F., and is fed at a rate of approximately 15 gallonsper minute to the organic ester feed-equipped tank 139, where it isreacted with organic ester, in this case, phenyl acetate, admitted at arate of 14 pounds per hour. Residence time is about four hours.

The alkylated mixture is fed at a rate of approximately 5,000 pounds perhour to the first solvent stripper 141, where it is blended with hotwater at 190 F. The watersoluble salts are extracted into the water.Steam and hydrocarbon vapor from 141' are injected to heat thesuspension to a temperature of 212 F., while the mixture is intenselyagitated. The isooctane flashes off, together with butadiene, isoprene,and any unreacted isopropanol and propylene, along with acetylenic andcyclopentadienic alcohols, and any unreacted volatile organic ester, inthis case, phenyl acetate. Approximately 98% of the total solvent isremoved in the first stripper. The vapor streams in line 142 amount toapproximately 12,000 pounds per hour. Isooctane, butadiene and isopreneare dried, condensed, separated in the solvent recovery system in ZoneD, and recycled. "Some butadiene dimer and heavy ends and any unreactedorganic ester and any heavy ends are removed in the heavy ends column185, and are purged.

A weight percent rubber crumb in water results, and is drawn off at thebottom of the stripper 141 via line 148, and sent to the second stagesolvent stripper or crum'b former 141', where the steam distillation isrepeated. The solvent content of the crumb at the beginning of thisstage is approximately weight percent, based on the rubber content. Theaqueous slurry of rubber emerging from this crumb former has the solventcontent reduced to 1 weight percent based upon the rubber content. Thevapor stream in line 142 contains essentially all of the solvent andmonomers originally present with the crumb, acetylenic andcyclopentadienic alcohols, and in addition any unreacted propylene andisopropyl alcohol formed by hydrolysis of the catalyst. The rubber crumbcontains only small amounts of molecular weight moderator and solvent.

The crumb slurry from the solvent stripper 141' passes through thescreen separator 152, removing rubber crumb which floats to the surfaceof the vessel. The liquid in the lower portion is recycled to the firstcrumb former 141.

Therubber crumb in the form of small particles containing approximately60 weight percent water is raked ofl, and enters the dewatering screen156, where it is contactedwith a screen of cold water at a rate ofapproximately 13 gallons per minute. This cools the crumb, preventsclogging of the screen, and reduces salt content. The underflow,consisting of water and a small amount of rubber fines, is pumped to thefines settler 155, where the rubber crumb overflows from the upperportion of the vessel back on the screen 156. The underflow is purged.The rubber crumb discharged from the screen is fed by the conveyor 160to the expeller 161, which reduces the water content by screwcompression from 60% to approximately 9%. The rubber crumb then entersthe expander 164 where, by compression at elevated pressures, the rubberis heated to approximately 300 B, so that upon discharge from theexpander, water as steam and solvent flash off. The product is thenbaled in the baler 167, and is ready for distribution.

Having regard to the foregoing disclosure, the following is claimed asthe inventive and patentable embodiments thereof:

1. In the continuous process for the preparation of alfin polymers fromalfin monomers which comprises continuously blending an organicunsaturated alfin monomer, alfin catalyst, molecular weight moderatorand solvent; continuously effecting the polymerization of alfin monomerat an elevated temperature at which the reaction proceeds whilecontrolling molecular weight by adjusting the amount of molecular weightmoderator; continuously separating volatile materials includingunreacted monomer, volatile low polymer, and solvent from the alfinpolymer reaction mixture; steam-distilling such volatile materials fromthe resulting dispersion, and washing and drying the alfin polymer; theimprovement which comprises continuously treating the reaction mixturewith from about 0.5 to about 15 weight percent, based on the alfinmonomer used, of an organic ester to convert organometallic compounds ofvolatile acetylenes and cyclopentadienes into alcohols and alcoholates;extracting water-soluble reaction products of volatile acetylenes andcyclopentadiene from the reaction mixture in water; and recoveringsolvent for reuse that is substantially free from acetylenes andcyclopentadiene.

2. The process of claim 1, wherein the molecular Weight of the polymeris controlled solely by adjustment of the proportion of molecular Weightmoderator, while maintaining reaction conditions, proportion ofcatalyst, and other process variables relatively constant.

3. The process of claim 1 wherein the polymerization is effected at atemperature within the range from about 40 to about 200 F.

4. The process of claim 1 wherein separation of volatiles by flashing iseffected at a temperature within the range from about 50 to about 275 C.and at a pressure differential before and after flashing within therange from about 35 to about 500 psi.

5. The process of claim 1, which includes quenching the reaction mixturewith water directly after the organic ester treatment, andsteam-distilling volatiles from the resulting mixture.

6. The process of claim 1 wherein the steam-distillation is carried outat a temperature within the range from about 50 to about C.

7. The process of claim 1 wherein the alfin catalyst is sodiumallyl-sodium isopropoxide.

8. The process of claim 1 wherein the molecular weight moderator is adihydroaromatic component.

9. The process of claim 1 wherein the dihydroaromatic component is adihydronaphthalene.

10. The process of claim 1 wherein the monomer is butadiene.

11. The process of claim 1 wherein the monomer is butadiene andisoprene.

12. The process of claim 1 wherein the monomer is butadiene and styrene.

13. The process of claim 1 wherein the alfin catalyst and sodiumdispersion used for making the alfin catalyst are prepared in the samesolvent employed for the alfin monomer polymerization reaction, andsolvent is recycled to all three steps.

14. The process of claim 1 wherein the moderator is in amount within therange from about 0.1 to about 10%.

15. The process of claim 1 wherein the amount of monomer employed iscalculated to give an alfin polymer concentration in the reactionsolution within the range from about 2 to about 25 weight percent.

16. A process in accordance with claim 1 in which an alfin polymer isproduced of from about 30 to about 110 Mooney.

17. A process in accordance with claim 1 in which volatiles are removedby quenching in hot water at from about 50 to about 130 C.

18. A process in accordance with claim 1 which includes washing thereaction mixture with water before separating solvent and unreactedmonomer.

19. A process in accordance with claim 18 in which the water is flowedcountercurrently to the reaction mixture during the washing.

20. A process in accordance with claim 1 in which the organic ester isan alkyl alcohol ester of an aliphatic acid, and has from one to abouttwenty carbon atoms.

21. A process in accordance with claim 1 in which the organic ester isan alkyl or aromatic alcohol ester of an aromatic or aliphatic acid, andhas from six to about twenty carbon atoms.

22. In the continuous process for the preparation of alfin polymers fromalfin monomers which comprises continuously blending an organicunsaturated alfin monomer, alfin catalyst, molecular weight moderatorand solvent; continuously passing the blend through a reaction zonewhile effecting the polymerization of alfin monomer at an elevatedtemperature at which the reaction proceeds while controlling molecularweight by the selected amount of molecular moderator; withdrawing fromthe reaction zone alfin polymer-containing reaction mixture having aMooney of at least 70% of the desired Mooney and an alfin polymerconcentration of from about 2 to about 25 weight percent; blending thereaction mixture with water at a temperature of from about 50 to about130 C.; injecting steam into the reaction mixture; and separating andrecovering volatile materials including unreacted monomer, volatile lowpolymer, and solvent from the quenched alfin polymer reaction mixture;and washing and drying the alfin rubber; the improvement which comprisescontinuously treating the reaction mixture with from about 0.5 to aboutweight percent, based on the alfin monomer used, of an organic ester toreact the organometallic compounds of volatile acetylenes andcyclopentadiene, including acetylides and v cyclopentadiene metalcompounds, to form the corresponding alcohols and alcoholates;extracting water-soluble reaction products of such volatile acetylenesand cyclopentadiene in 'water; and separating and recovering monomer andsolvent for reuse that are substantially free from acetylenes andcyclopentadiene. H

23. A process in accordance with claim 22 in which alfin catalyst isprepared in an inert solvent for use in the process, starting fromsodiumsuspended in an inert solvent, methyl-n-alkyl carbinol. and olefin, andsuch solvent, carbinol and olefin are also recovered in the steamdistillation, and at least the solvent recycled. 24. A process inaccordance with claim 22, which includes flashing of the reactionmixture at .a temperature within the range from about to about 275 C.and at a pressure dilferential before and after flashing Within therange from about 35 toabout 500 p.s.i. before blending the reactionmixture with water, and separately recovering dry monomer.

25. A process in accordance with claim 22 in which I the organic esteris an alkyl alcohol ester of an aliphatic acid, and has from one toabout twenty carbon atoms.

26. A process in accordance with claim 22 in which the organic ester isan alkyl or aromatic alcohol ester, of an aromatic or aliphatic acid,and has from six to about twenty carbon atoms.

References Cited JOSEPH L. SHOFER, Primary Examiner R. A. GAITHER,Assistant Examiner US. Cl. X.R.

